Interesting European exploration documentary?

I'm going to be out of the classroom on a day-long field trip next week and I need to find something easy for a sub to give the world history kiddos. We're currently talking about European exploration into Asia and I was thinking about finding a fun documentary for them to watch about Christopher Columbus, Bartolomeu Dias, or Vasco de Gama. I also entertained the idea of a documentary about Zheng He and the Ming Dynasty. I would be open to any of these topics as long as its interesting enough to keep their attention. The class periods are 50 minutes, so it would be great if there was one that would fit in that time.